Moving a camel through the eye of a needle with GNSS

作者：Beate Wesenigk

TheNEPTUN shipyardis part of the MEYER Group based in Papenburg, Northern Germany, and enormous floating objects are constructed in it – Floating Engine Room Units (FERUs), the ‘power stations’ for giant cruise ships. Specialised in FERUs, this shipyard in northern Germany, faces a big challenge – FERUs are not constructed in dry docks, but in various production halls above the water line. To bridge the2-metreheight差异，开发了浮动系统。为了安全地从生产大厅和降低系统中安​​全地操纵Ferus，Neptun Shipyard开始使用Leica Geosystems GNSS技术。

Blind trust as a prerequisite

The lowering system is a shippable floating dock. It consists of a reinforced concrete pontoon with additional superstructures on top. The float itself is150 m long,55 m wide and 7.5 m high。Inside the pontoon, there are water tanks. During docking, FERUs are fixated with the help of steel-cable winches. The lowering system has a dedicated control room located in the front tower on the starboard side. From there, all systems are monitored and controlled.

当准备将其运输到现场时，首先在液压系统的帮助下首先将FERU移到生产大厅内。然后，它滑过陆地上的一条硅胶涂层路径，直到降低系统在水中等待的码头墙。当船放在降低系统上时，拖船拉动了巨大的Feru - 重量超过40,000吨此时 - 就在16米深底座。然后，必须将降低系统正确定位到几厘米，并以某种方式固定在上下移动的唯一选择。

Subsequently, the tanks are flooded, thus sinking the entire lowering system. Ultimately, only2 m of the 18-msuperstructure protrudes above the water. As soon as there is enough water on the deck, the tug boat captains receive their go-ahead. The FERU is then moored at the bow and the stern.

This undocking process itself can be likened to the metaphor of a camel going through the eye of a needle describing a very narrow opening – the distance between the undocked ship and the superstructures is only120 cm在最。拖轮船长和驾驶员top the FERU have no means of orienting themselves towards the port- or starboard side. The captain at the stern only sees metres upon metres of grey metal wall towering in front of him. Both captains need to blindly trust the pilot. This means the exact position of the FERU atop the lowering system must be known. Otherwise, avoiding collisions with the superstructures is impossible and these would inevitably damage the FERU as well as the lowering system.

Using GNSS technology for construction sites

A GNSS-supported measurement process with Leica Geosystems technologies is now used in all the steps. Multi-frequency GNSS antennae were installed on the starboard-side bow and stern of the superstructures on the lowering system. The accompanying dual GNSS receiverLeica iCG 80安装在控制室中。该装置最初是由Leica Geosystems开发的，用于土木工程中的重型建筑机械，不仅可以确定确切的位置，而且还可以预测潜在的运动。随后，通过使用A的一次性测量测量来确定触角与降低系统相关的相对位置Leica Nova TS60total station. In one of the shipyard's halls, aLeica Viva GS10GNSS high-precision receiver was installed in a relatively sheltered spot, serving as a precise-measured fixed point.

Feru 1396是新系统的第一个不可锁定的电站，将成为世界上最大的邮轮公司最新的邮轮之一的核心。首先在降低系统上的先前测量位置安装了两个ICG80 GNS接收器，并激活了控制室中的接收器。使用此安装，可以将FERU从生产厅移动到降低系统上的精确位置。为了从降低系统中解除FERU，将两个触角安装在其上。

控制室中使用的降低系统的控制软件将GNSS数据，地面和海上图链接起来，提供实时数据以及预测降低系统和FERU的投影运动的数据，并在撤消过程中向所有参与者提供。为了立即做出反应，并给出适当的说明，飞行员和拖船队长使用Leica CS35现场片剂。除了在其CS35现场平板电脑上的实时数据和移动预测外，飞行员和拖船队长还确切地看到了他们要踩踏到右舷和端口以使降低系统没有损坏的情况。

Navigating FERU 1396 out of the eye of the needle took only 10 minutes – a time that would have been impossible for a safe undocking, especially at a day with winds of force six because, due to its dimensions, the FERU poses such a big target for the wind.

Faster + more flexible = more profits

The MEYER Group has been successfully using measurement solutions from Leica Geosystems for many years. During the conception phase, GNSS solutions from various suppliers were evaluated. The main criteria were:

• Positioning accuracy of 2 to 3 cm,even on moving ground
• Immunity to environmental factors, such as temperature fluctuations and salt water
• 无线和无线电数据传输。

The survey team headed by Ralph Zimmermann decided for the Leica Geosystems solution. The iCG80 GNSS receivers were developed to withstand harsh conditions on construction sites, work error-free from-20 C to + 40 C并且是飞溅water resistant。

Lars Wegener and Kevin Schemmel, part of the survey team at NEPTUN shipyard, reported,“Relocation of 1396 went well.”Zimmermann expanded,“With the help of this technology, we have literally made big things happen. You could clearly see that we practise the motto of the MEYER Group, ‘Stronger together’, because, in addition to the workers of both shipyards, many specialists were involved; experts for nautical map technology, classical coastal navigation and tugging methods.”

This system benefits the MEYER Group in various ways for ongoing tasks as well as for future projects. The entire process of moving and undocking FERUs has become much safer because of the provided real-time positions, movement projections and calculations for tug control help to avoid collisions. Furthermore, it is possible to move and undock objects that extend beyond the bow and stern of the lowering system. The speed, precision and reliability of the system unaltered by weather conditions is a perfect fit for MEYER Group who plans to build three cruise ships in Papenburg starting in 2019 and, in the future, two per year in Turku, Finland.